JP2012161956A - Double mixing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a double mixing method that can secure properties and quality such as a slump value and a flow value of fresh concrete (or mortar) to certainly obtain superior characteristics after a secondary mixing.SOLUTION: The production of mortar and concrete is carried out by forming a strong shell construction in the aggregate surroundings by separating the mixing water into the primary water and the secondary water, adding the primary water to the aggregate, carrying out adjustment mixing at an isolated location from the concrete/mortar placing location of the construction site, by adding the secondary water to the primary mixed product produced by the primary mixing until carry in it to the concrete/mortar placing location and carrying out primary mixing by adding hydraulic setting substance of the powder, and carrying out secondary mixing on the way of conveyance to the concrete/mortar placing location.

Description

  The present invention relates to a divided kneading method.

  As is well known, mortar and concrete consist of a predetermined amount of water (mixed water), aggregate (fine aggregate, coarse aggregate) and cement (powdered hydraulic substance) determined according to the desired physical properties. ). In addition, various admixtures (admixtures (powdered water) are used to improve the physical properties after curing, such as improved workability and pumpability, improved strength and durability, and adjustment of the setting speed. It is manufactured by mixing hard substances) and admixtures. The admixture is used for the purpose of suppressing an increase in initial temperature associated with the hydration reaction, improving fluidity, and making the structure dense.

  Here, the applicant of the present application divides the kneaded water into primary water and secondary water, and after adding and kneading the primary water to the aggregate, kneading with cement (primary kneading), Finally, by applying secondary water and kneading (secondary kneading), an application was filed for the split kneading method (SEC (registered trademark) method) that can produce mortar and concrete with excellent physical properties. (For example, refer to Patent Document 1).

  Specifically, in this divided kneading method, when primary kneading is added to the aggregate and adjustment kneading is performed, moisture uniformly adheres around the aggregate. When cement is added and primary kneading is performed, a cement paste with a relatively small water cement ratio is fixed around the aggregate to form a strong shell (shell formation layer) and granulate (shell formation) Is formed). Homogeneous concrete can be obtained by adding secondary water to the aggregated and cemented shells in this way and adding secondary water in the amount of primary water subtracted from the total amount of water to be added (mixed water). (Or mortar) can be obtained.

  The concrete produced in this way has a three-dimensional network structure due to the formation of a shell around the aggregate, compared to the conventional one produced by batch mixing. The rise is suppressed and material separation and bleeding are reduced. Moreover, since the shell-forming layer adheres firmly to the aggregate and the cement paste is uniformly filled between the granulated bodies at the time of secondary kneading, the strength characteristics (compressive strength and the like) as concrete are improved. Furthermore, the shell-forming layer around the aggregate reduces friction between the aggregates, so that the fluidity under vibration is improved, and workability and pumpability are improved.

  On the other hand, the applicant of the present application has also filed an application relating to a divided kneading method for application to concrete construction at a construction site considerably separated from a batcher plant (raw material preparation position) (see Patent Document 2). In this divided kneading method, primary kneading is performed at a batcher plant, the kneaded material in the state of primary kneading is carried to the construction site (including the vicinity of the construction site), and secondary water is added at the construction site to perform secondary kneading. I do.

  And when such a divided kneading method is applied to the spraying construction in the tunnel, the primary kneaded material produced by the primary kneading in the batcher plant outside the mine is near the excavation face by a truck mixer (portable agitator). Transported to the construction site and added secondary water at the construction site for secondary kneading. Here, in the primary kneaded material, a cement paste having a relatively low water cement ratio is fixed around the aggregate to form a shell, and the resistance when the stirring blade is rotated and mixed is the highest (mixing energy). Is in the capillary state. For this reason, there is almost no moisture movement between aggregate particles due to vibration during transportation and gravity conditions during standby at the construction site. Thereby, even if it keeps in the truck mixer truck for a long time in the state of primary kneaded material, the uniform state in which the shell formation around the aggregate was formed stably can be maintained. And by performing secondary kneading by adding secondary water at the construction site, it is not affected by the progress status of excavation construction and the distance from the batcher plant, and the tunnel construction with excellent strength is performed. Is possible.

Japanese Patent No. 4249176 Japanese Patent No. 4242898

  However, in the divided kneading method in which secondary water is added and secondarily kneaded at the construction site as described above, the hydration reaction of the primary kneaded product proceeds until the second kneading at the construction site. If it is too much, the properties (slump value, etc.) of the concrete after the secondary kneading may be affected. In other words, there is a limit to the time that can be maintained in the state of the primary kneaded material, and there is room for improvement in terms of ensuring the quality of the concrete after the secondary kneading (in order to obtain excellent characteristics of the divided kneading). Was left.

  In addition, for example, when the amount of powder (hydraulic substance such as cement) increases (the richer the mixture), the longer the primary kneading time becomes, the more the aggregate (shell-forming body) forms the shell by primary kneading. ) There are cases where the particles stick together and granulate. When the shells are granulated, there is a risk that the excellent characteristics of the divided kneading cannot be obtained.

  Furthermore, for example, when the primary kneaded product is transported to the construction site by an agitator car, and secondary water is added at this construction site, and the secondary kneading is performed by the high speed stirring of the agitator car, the high speed stirring of the agitator car Causes a loud noise. For this reason, depending on the conditions at the construction site, secondary kneading may not be possible at the construction site, and it has been strongly desired to be able to respond flexibly even in such a case.

  In order to solve the above problems, the present invention provides the following means.

  In the divided kneading method of the present invention, the kneading water is divided into primary water and secondary water, and the primary water is added to the aggregate in a place separated from the concrete / mortar placement site at the construction site, and adjustment kneading is performed. In addition, the primary kneading is performed by the primary kneading until a powdery hydraulic substance is added and the primary kneading is performed to form a strong shell around the aggregate and the concrete is put into the concrete / mortar placement site. Mortar or concrete is produced by adding secondary water to the object and performing secondary kneading in the middle of conveyance to the concrete / mortar placement site.

  In the divided kneading method of the present invention, primary kneading is performed with a batcher plant mixer to form a shell around the aggregate and secondary water is added to the mixer, and immediately after that, the kneaded product is It is desirable to discharge from the mixer to a portable stirrer, and to carry out secondary kneading during the transport to the concrete / mortar placement site by the portable stirrer.

  Further, in the divided kneading method of the present invention, primary kneading is performed with a mixer of a batcher plant to form a shell around the aggregate, and the primary kneaded product manufactured by the batcher plant is transferred from the mixer to a portable agitator. The secondary kneaded product may be discharged, and secondary water may be added to the primary kneaded product with the portable stirrer, and secondary kneading may be performed while being transported to the concrete / mortar placement site with the portable stirrer.

  Further, in the divided kneading method of the present invention, primary kneading is performed with a mixer of a batcher plant to form a shell around the aggregate, and the primary kneaded product manufactured by the batcher plant is discharged from the mixer, and the concrete / Secondary kneading may be performed by adding secondary water using a separately prepared stirring facility during transportation to the mortar placement site.

  In the divided kneading method of the present invention, secondary water is added to the primary kneaded material at any time and place until it is carried into the concrete placement site (concrete / mortar placement site) at the construction site. By performing the next kneading, it is possible to prevent the hydration reaction of the primary kneaded product from proceeding excessively. As a result, properties and quality such as slump value and flow value of fresh concrete (or mortar) after secondary kneading can be secured, and excellent properties of divided kneading can be surely obtained.

  In addition, by performing secondary kneading while transporting to the concrete placement site at the construction site, primary kneading is performed in comparison with the case where secondary kneading is performed by adding secondary water at the conventional construction site. It is possible to shorten the time for maintaining this state, and it is possible to reliably prevent the aggregates (shells) forming the shells from being primary kneaded and granulated. Also from this point, the properties and quality of fresh concrete (or mortar) after secondary kneading can be ensured, and it is possible to surely obtain excellent characteristics of divided kneading.

  Furthermore, in the divided kneading method of the present invention, the secondary kneading is performed in the middle of conveyance to the concrete placement site at the construction site, thereby maintaining the property of the primary kneaded material and the fresh concrete after the second kneading (or Depending on the persistence of the properties of the mortar, it is possible to arbitrarily determine where the secondary kneading is performed during conveyance. Thereby, it is possible to flexibly cope with the conditions at the construction site such as noise countermeasures near the concrete placement site, parking spaces, and the presence or absence of a secondary water supply device.

  Also, by performing secondary kneading while transporting to the concrete placement site at the construction site, primary kneading and secondary kneading are performed at the batcher plant as before, or secondary water is added to the primary kneaded material at the construction site. Compared with the case where secondary kneading is performed, the kneading time in the mixer can be shortened, and the time for carrying the primary kneaded material to the construction site can be effectively utilized for the secondary kneading. As a result, it is possible to efficiently perform the divided kneading while reducing the time for the divided kneading while ensuring the excellent characteristics of the divided kneading.

  In addition, the primary kneading is performed at a location separated from the concrete placement site at the construction site, and the secondary kneading is performed during the transfer to the concrete placement site, so that it is not a batcher plant that supports the split kneading method. Even so (primary kneading can be performed using a normal (batch kneading) batcher plant), it becomes possible to carry out divided kneading efficiently.

  In addition, fresh concrete produced by a batch kneading method is usually required to be placed within one and a half hours after kneading. On the other hand, in the present invention, primary kneading is performed at a location separated from the concrete placement site at the construction site, and secondary kneading is performed at any time and place until it is carried into the concrete placement site at the construction site. Fresh concrete (or mortar) can be manufactured. And even if it is a case where fresh concrete is manufactured by performing secondary kneading in the stage where several hours have passed since primary kneading, the properties and quality of fresh concrete after secondary kneading can be secured. For this reason, in the division | segmentation kneading method of this invention, it becomes possible to lengthen the usable time of fresh concrete (time from manufacturing fresh concrete after secondary kneading to placing it).

It is an experimental result (slump, measurement result of slump loss) which shows the predominance of the division kneading method concerning one embodiment of the present invention. It is a figure which shows the time-dependent change of the voltage value of the primary kneaded material manufactured with the division | segmentation kneading method concerning one Embodiment of this invention. It is a figure which shows a time-dependent change of the temperature of the primary kneaded material manufactured with the division | segmentation kneading method concerning one Embodiment of this invention. It is a figure which shows an example of the measuring apparatus used when measuring the voltage value of the primary kneaded material manufactured with the division | segmentation kneading method concerning one Embodiment of this invention.

  Hereinafter, the divided kneading method according to an embodiment of the present invention will be described. Here, in this embodiment, the powdery hydraulic substance is described as being simply cement, but the hydraulic substance according to the present invention is a hydraulic admixture such as blast furnace slag, fly ash, or silica fume. It may be a powdery substance (powder) in which a cement such as ordinary Portland cement is mixed. In addition, although this embodiment demonstrates as what manufactures concrete by a division | segmentation kneading method, even when manufacturing mortar, it is the same as this embodiment by carrying out similarly to this embodiment demonstrated below. It is possible to obtain an operational effect.

  In the divided kneading method of this embodiment, the aggregate is poured into the mixer of the batcher plant provided at a place separated from the concrete placing place (concrete / mortar placing place) at the construction site and the primary water is poured. , Make adjustments. Next, cement (hydraulic substance) is added and primary kneading is performed to form a strong shell around the aggregate.

  Here, a method of determining the primary water amount will be described by taking a method of determining the primary water amount by a torque test and a centrifugal force test as an example. In the torque test, cement and water are kneaded while changing the amount of water to be added, and the amount of water that maximizes the binding force between the cement paste particles and maximizes the kneading energy (capillary state) is obtained. On the other hand, in the centrifugal force test, part of the primary water is adsorbed on the aggregate during the primary kneading, so the mortar is actually produced to determine the amount of adsorbed water.

Then, the water powder ratio α at which the powdery hydraulic substance obtained by the torque test becomes a capillary state and the adsorbed water ratio β _OH of the fine aggregate obtained by the centrifugal force test are applied to the following formula (1). The optimum primary water amount W1 is obtained. In the formula (1), S represents the unit fine aggregate amount, and P represents the unit powder amount.
W1 = α × P + β _OH × S (1)

  The primary water is uniformly distributed at the aggregate interface by introducing the primary water amount determined in this way and carrying out adjustment kneading. For this reason, when cement is added and primary kneading is performed, the primary water and the cement at the aggregate interface are mixed together to form a uniform capillary, and a strong shell is formed.

  In the present embodiment, the primary water amount is subtracted from the total blended water amount (total mixed water amount) in the batcher plant mixer at the stage where the primary kneading is performed by the batcher plant mixer and the shell is formed around the aggregate. Of secondary water (W2).

  Next, the primary kneaded material manufactured in the batcher plant and added with the secondary water (W2) is discharged from the mixer of the batcher plant to a portable agitator such as a truck mixer truck (agitator truck). And with this portable stirrer, the primary kneaded material to which the secondary water (W2) is added is conveyed (transported) to the concrete placement site at the construction site. Moreover, with a portable stirrer, the primary kneaded material is agitated during the conveyance to the concrete placement site at the construction site to perform secondary kneading.

  In this embodiment, primary kneading is performed by a batcher plant mixer to form a shell around the aggregate, and secondary water (W2) is added to the batcher plant mixer, and immediately after that, the kneaded product is mixed with the mixer. Then, it was discharged to a portable stirrer and secondary kneading was carried out with a portable stirrer during the transfer to the concrete placement site at the construction site. On the other hand, primary kneading is performed with a batcher plant mixer to form a shell around the aggregate, and the primary kneaded product produced in the batcher plant is discharged from the mixer to a portable stirrer, which is then used as the primary stirrer. You may make it add secondary water to a kneaded material, and may perform secondary kneading in the middle of conveyance to a concrete placement place with a portable stirrer. At this time, water in a relatively small tank appropriately mounted on the truck mixer truck may be used as secondary water.

  Here, Case 1 in which aggregate, kneaded water and cement are kneaded together, and after adding primary water to the aggregate and adjusting and kneading, cement is added and primary kneaded, and secondary water is added and kneaded secondary. The concrete is manufactured in three cases of Case 2 by the standard divided kneading method and Case 3 by the divided kneading method of this embodiment, and the results of the fresh concrete test will be described.

  In Case 1, concrete having the composition shown in Table 1 is kneaded by the usual batch kneading method, and after the kneaded material is transferred to an agitator car, it is discharged after performing high speed stirring for 30 seconds with the agitator car. Fresh properties were measured by a fresh concrete test. In addition, high-speed stirring was performed for 30 seconds every 30 minutes after the kneading, the sample concrete was discharged each time, the fresh properties were measured, and the change with time of the slump was confirmed.

  In Case 2, concrete of the composition shown in Table 1 is kneaded and mixed by a standard split kneading method, and transferred to an agitator car. And like Case 1, it discharged after performing high-speed stirring for 30 seconds with an agitator vehicle, and the fresh property of this sample concrete was measured by the fresh concrete test. In addition, high-speed stirring was performed for 30 seconds every 30 minutes after the kneading, the sample concrete was discharged each time, the fresh properties were measured, and the change with time of the slump was confirmed.

  In Case 3, the primary kneaded material (concrete) subjected to the primary kneading is transferred to an agitator car based on the formulation shown in Table 1, and is put on standby with low speed stirring assuming a transportation time of 60 minutes. Then, after 60 minutes, the secondary water was put into the agitator car, and after high-speed stirring for 120 seconds, it was discharged, and the fresh property of this sample concrete was measured by a fresh concrete test. In addition, as in Cases 1 and 2, high-speed stirring was performed for 30 seconds every 30 minutes after kneading, and each time the sample concrete was discharged, fresh properties were measured, and changes in the slump over time were confirmed.

  The test results are shown in Table 2, Table 3 and FIG. In Tables 2 and 3, Sl is slump, and Sf is slump flow. From these charts, the slump in Case 3 and its change with time are not inferior to those of Case 1 of normal batch kneading and Case 2 of standard divided kneading method. That is, in the case of Case 3, it is finished to primary kneading by the mixer of the batcher plant, and the constituent materials of concrete (cement, fine aggregate, coarse aggregate and primary water) are mixed evenly. And since subsequent secondary water injection and high-speed agitation in the agitator vehicle imparts fluidity to the concrete, even in the case 3 split kneading method, sufficient agitation is performed and concrete having the same properties as Case 1 and Case 2 is obtained. Manufactured. Therefore, it was confirmed that the concrete can be suitably produced even by using the divided kneading method of the present embodiment.

  As described above, in the divided kneading method of the present embodiment, secondary water is added to the primary kneaded material at any time and place until it is carried into the concrete placement site of the construction site. Next kneading was done. As a result, it is possible to prevent the hydration reaction of the primary kneaded product from proceeding excessively, so that the properties and quality such as slump value and flow value of fresh concrete (or mortar) after secondary kneading can be ensured, and divided kneading is ensured. Excellent characteristics can be obtained.

  In addition, by performing secondary kneading while transporting to the concrete placement site at the construction site, primary kneading is performed in comparison with the case where secondary kneading is performed by adding secondary water at the conventional construction site. It is possible to shorten the time for maintaining this state, and it is possible to reliably prevent the aggregates (shells) forming the shells from being primary kneaded and granulated. Also from this point, the properties and quality of the fresh concrete after the secondary kneading can be ensured, and the excellent characteristics of the divided kneading can be surely obtained.

  Furthermore, by carrying out secondary kneading in the middle of conveyance to the concrete placement site at the construction site, the second kneading can occur anywhere during the conveyance depending on the durability of the properties of the primary kneaded material and the properties of the fresh concrete after the second kneading. It is possible to arbitrarily decide whether to perform the next kneading. As a result, when using an agitator vehicle as a portable agitator, it is possible to flexibly respond to the conditions at the construction site, such as noise countermeasures near the concrete placement site, parking space, and the presence or absence of a secondary water supply device. .

  Also, by performing secondary kneading while transporting to the concrete placement site at the construction site, primary kneading and secondary kneading are performed at the batcher plant as before, or secondary water is added to the primary kneaded material at the construction site. Compared with the case where secondary kneading is performed, the kneading time in the mixer can be shortened, and the time for carrying the primary kneaded material to the construction site can be effectively utilized for the secondary kneading. As a result, it is possible to efficiently perform the divided kneading while reducing the time for the divided kneading while ensuring the excellent characteristics of the divided kneading.

  In addition, the primary kneading is performed at a location separated from the concrete placement site at the construction site, and the secondary kneading is performed during the transfer to the concrete placement site, so that it is not a batcher plant that supports the split kneading method. Even so (primary kneading can be performed using a normal (batch kneading) batcher plant), it becomes possible to carry out divided kneading efficiently.

  When secondary water is added to the primary kneaded product using a batcher plant mixer and discharged from the mixer, a supply bottle for measuring and charging the secondary water is added to the normal (batch kneading) batcher plant. This can be handled by making minor modifications. Also, when primary kneading is performed with a batcher plant mixer, the produced primary kneaded product is discharged from the mixer to a portable stirrer, and when secondary kneading is performed by adding secondary water with this portable stirrer, The batcher plant can be used without modification.

  Furthermore, as described above, in the divided kneading method of the present embodiment, the primary kneading is performed at a location separated from the concrete placement site at the construction site, and it is optional until it is carried into the concrete placement site at the construction site. Fresh concrete can be produced by performing secondary kneading at the time and place.

  Here, since the state of the primary kneaded product obtained by primary kneading has a small water cement ratio (20 to 30%), the progress of the hydration reaction of the hydraulic substance powder such as cement is slow. On the other hand, normal lump-mixed concrete has a water-cement ratio of 45 to 55%, so the hydration reaction proceeds quickly, and it is usually necessary to cast within 1.5 hours from completion of mixing. .

  On the other hand, in the present invention, it is shown below that the properties of the divided kneaded concrete can be maintained even if the kneaded material in the primary kneaded state is subjected to secondary kneading after several hours.

  Here, FIG. 2 shows the results of measuring the voltage generated at both ends of the resistor placed in series in the circuit over time from the kneading of the primary kneaded in order to obtain the change in the electrical resistance of the primary kneaded product. 3 shows the result of measuring the temperature of the primary kneaded material over time from the kneading of the primary kneading, and FIG. 4 shows these measuring devices. In addition, the electrical resistance value measuring container in the measuring device of FIG. 4 is specified in the Japan Society of Civil Engineers standard (JSCE-C-506-2003): “Method for testing density and water absorption rate of slab fine aggregate for concrete by electrical resistance method”. The measured electrical resistance measurement container is used.

  From FIG. 2, it was confirmed that the voltage value of the primary kneaded product did not change significantly during the 5 hours after the primary kneading. This is that the resistance value of the primary kneaded product does not change, and it indicates that the water in the shell-forming part has not decreased due to the hydration reaction. Further, from FIG. 3, it was confirmed that the temperature of the primary kneaded product gradually increased from the kneading of the primary kneading and showed a peak at the stage where 9 hours had elapsed from the kneading. This shows that the heat generated by the hydration reaction is small compared to the peak for several hours after the primary kneading, and the hydration reaction does not proceed. Such changes in electrical resistance and temperature of the primary kneaded product are due to the hydration reaction of the cement.

  From this, it can be said that the properties and quality of the fresh concrete after the secondary kneading can be ensured even when the fresh kneading is produced by performing the second kneading after a few hours have passed since the primary kneading. Furthermore, from this, in the divided kneading method of the present embodiment, it is possible to lengthen the usable time of fresh concrete (the time from production of primary concrete after secondary kneading to placement). It becomes possible.

  As mentioned above, although one Embodiment of the division | segmentation kneading method concerning this invention was described, this invention is not limited to said one Embodiment, In the range which does not deviate from the meaning, it can change suitably.

  For example, in the present embodiment, the primary kneaded material is discharged from a batcher plant mixer to a portable stirrer, and this kneading is performed on the assumption that secondary kneading is performed during conveyance to a concrete placement site. It was. On the other hand, the primary kneaded material may be discharged from the mixer of the batcher plant, and the secondary kneading may be performed by adding secondary water using a separately prepared stirring facility during the transfer to the concrete placement site. Even if it does in this way, of course, it is possible to obtain the same effect as this embodiment.

Claims (4)

Divide the water into primary water and secondary water,
In a place separated from the concrete / mortar placement site at the construction site, primary water is added to the aggregate and kneaded, and a powdered hydraulic substance is added and primary kneaded to create a strong shell around the aggregate Form the
Add secondary water to the primary kneaded product produced by the primary kneading and carry out secondary kneading in the middle of conveyance to the concrete / mortar placing place until the concrete / mortar placing place. A split kneading method characterized by producing mortar or concrete. In the divided kneading method according to claim 1,
Primary kneading is performed in a batcher plant mixer to form a shell around the aggregate, and secondary water is added to the mixer. Immediately after that, the kneaded product is discharged from the mixer to a portable agitator, A divided kneading method characterized in that secondary kneading is carried out in the middle of conveyance to the concrete / mortar placing place by a portable agitator. In the divided kneading method according to claim 1,
A primary kneading is performed with a mixer of a batcher plant to form a shell around the aggregate, and a primary kneaded product manufactured in the batcher plant is discharged from the mixer to a portable agitator, and the primary kneading is performed with the portable agitator. A secondary kneading method characterized in that secondary water is added to an object and secondary kneading is carried out during conveyance to the concrete / mortar placement site by the portable stirrer. In the divided kneading method according to claim 1,
A primary kneading is performed with a mixer of a batcher plant to form a shell around the aggregate, and the primary kneaded product manufactured by the batcher plant is discharged from the mixer and is separately transported to the concrete / mortar placement site. A divided kneading method characterized in that secondary kneading is performed by adding secondary water using a prepared stirring facility.

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